Hi, BetNC:
Carrots, lettuce and potatoes do very well in containers (potatoes need a larger container, though). For squash, look for a "bush" type that doesn't grow quite as large as others. Burpees sells a sweet corn that is supposed to be specifically for containers--I think it's called "On-deck" or something similar. Supposed to have a higher yield in smaller spaces.
I grow all of my veggies in containers, and it's amazing what can be done with the right size container and proper water/fertilization.
